Ignition safety devices (ISDs) prevent an unintended functioning of a rocket motor, missile motor, or other energetic device (i.e., one that utilizes a propellant or pyrotechnic output) through an interruption of a pyrotechnic train, an interruption of a firing energy train, or the control of the energy required to arm the ISD and function the initiator. MIL-STD-1901A (June 2002) is an exemplary Design Criteria Standard for a Munition Rocket and Missile Motor Ignition System Design. This standard requires that a rocket motor initiator be either out-of-line or require greater than 500 Volts to initiate the rocket motor. Most conventional systems are either not compliant with these requirements, are inconveniently large, expensive, and/or complex. Conventional systems which are compliant with MIL-STD-1901A requirements are typically made with conventional metal parts assemblies produced by conventional precision machining and attachment.
By contrast, MEMS are miniaturized, mass-produced devices (i.e., micrometer dimensions) that may include actuators, sensors, and other mechanical structures. MEMS are typically fabricated by bulk-etching a silicon substrate or depositing layers of polysilicon, oxides, metals, and the like atop a silicon substrate. Typical MEMS actuation mechanisms include electrostatic, magnetic, and thermal. A MEMS thermal actuator is a microelectromechanical device that typically generates motion by thermal expansion amplification. A small amount of thermal expansion of one part of the device translates to a large amount of deflection of the overall device. MEMS thermal actuators are typically fabricated from doped single crystal silicon or polysilicon as a complex compliant member.